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Commit 3c6296f7 authored by Steven Rostedt (Red Hat)'s avatar Steven Rostedt (Red Hat) Committed by Steven Rostedt
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ring-buffer: Remove useless unused tracing_off_permanent() 



The tracing_off_permanent() call is a way to disable all ring_buffers.
Nothing uses it and nothing should use it, as tracing_off() and
friends are better, as they disable the ring buffers related to
tracing. The tracing_off_permanent() even disabled non tracing
ring buffers. This is a bit drastic, and was added to handle NMIs
doing outputs that could corrupt the ring buffer when only tracing
used them. It is now obsolete and adds a little overhead, it should
be removed.

Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 289a5a25

include/linux/kernel.h

+0 −6
Original line number Diff line number Diff line
@@ -532,12 +532,6 @@ bool mac_pton(const char *s, u8 *mac); 
 *

 * Most likely, you want to use tracing_on/tracing_off.

 */

#ifdef CONFIG_RING_BUFFER

/* trace_off_permanent stops recording with no way to bring it back */

void tracing_off_permanent(void);

#else

static inline void tracing_off_permanent(void) { }

#endif



enum ftrace_dump_mode {

	DUMP_NONE,

kernel/trace/ring_buffer.c

+0 −61
Original line number Diff line number Diff line
@@ -115,63 +115,11 @@ int ring_buffer_print_entry_header(struct trace_seq *s) 
 *

 */



/*

 * A fast way to enable or disable all ring buffers is to

 * call tracing_on or tracing_off. Turning off the ring buffers

 * prevents all ring buffers from being recorded to.

 * Turning this switch on, makes it OK to write to the

 * ring buffer, if the ring buffer is enabled itself.

 *

 * There's three layers that must be on in order to write

 * to the ring buffer.

 *

 * 1) This global flag must be set.

 * 2) The ring buffer must be enabled for recording.

 * 3) The per cpu buffer must be enabled for recording.

 *

 * In case of an anomaly, this global flag has a bit set that

 * will permantly disable all ring buffers.

 */



/*

 * Global flag to disable all recording to ring buffers

 *  This has two bits: ON, DISABLED

 *

 *  ON   DISABLED

 * ---- ----------

 *   0      0        : ring buffers are off

 *   1      0        : ring buffers are on

 *   X      1        : ring buffers are permanently disabled

 */



enum {

	RB_BUFFERS_ON_BIT	= 0,

	RB_BUFFERS_DISABLED_BIT	= 1,

};



enum {

	RB_BUFFERS_ON		= 1 << RB_BUFFERS_ON_BIT,

	RB_BUFFERS_DISABLED	= 1 << RB_BUFFERS_DISABLED_BIT,

};



static unsigned long ring_buffer_flags __read_mostly = RB_BUFFERS_ON;



/* Used for individual buffers (after the counter) */

#define RB_BUFFER_OFF		(1 << 20)



#define BUF_PAGE_HDR_SIZE offsetof(struct buffer_data_page, data)



/**

 * tracing_off_permanent - permanently disable ring buffers

 *

 * This function, once called, will disable all ring buffers

 * permanently.

 */

void tracing_off_permanent(void)

{

	set_bit(RB_BUFFERS_DISABLED_BIT, &ring_buffer_flags);

}



#define RB_EVNT_HDR_SIZE (offsetof(struct ring_buffer_event, array))

#define RB_ALIGNMENT		4U

#define RB_MAX_SMALL_DATA	(RB_ALIGNMENT * RINGBUF_TYPE_DATA_TYPE_LEN_MAX)
@@ -2728,9 +2676,6 @@ ring_buffer_lock_reserve(struct ring_buffer *buffer, unsigned long length) 
	struct ring_buffer_event *event;

	int cpu;



	if (ring_buffer_flags != RB_BUFFERS_ON)

		return NULL;



	/* If we are tracing schedule, we don't want to recurse */

	preempt_disable_notrace();
@@ -2992,9 +2937,6 @@ int ring_buffer_write(struct ring_buffer *buffer, 
	int ret = -EBUSY;

	int cpu;



	if (ring_buffer_flags != RB_BUFFERS_ON)

		return -EBUSY;



	preempt_disable_notrace();



	if (atomic_read(&buffer->record_disabled))
@@ -4350,9 +4292,6 @@ int ring_buffer_swap_cpu(struct ring_buffer *buffer_a, 


	ret = -EAGAIN;



	if (ring_buffer_flags != RB_BUFFERS_ON)

		goto out;



	if (atomic_read(&buffer_a->record_disabled))

		goto out;